JP2009194368A - Lithographic apparatus for suppressing focus error, using substrate topology with regulated exposing slit shape, and method of manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithographic apparatus improved in the curvature compensation of a substrate. <P>SOLUTION: A lighting system is configured to form a slit type image on the flat plane of a patterning device. The slit type image has a curved shape with a slit curvature in a scanning direction, a length LS in the scanning direction, and a rectangular width for a scanning direction Y. The slit type image is configured to generate a curved pattern image of a patterned radiation beam on the image flat plane of a projection system. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a lithographic apparatus and a method for manufacturing a device.

A lithographic apparatus is a machine that applies a desired pattern onto a substrate, generally onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that case, a patterning device, also referred to as a mask or a reticle, is used to generate a circuit pattern to be formed on an individual layer of the IC. The generated pattern is transferred to a target portion (eg including part of one or more dies) on a substrate (eg a silicon wafer). Pattern transfer is typically performed via imaging onto a layer of radiation sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Known lithographic apparatus include a so-called stepper in which each of the target portions is irradiated by exposing the entire pattern to the target portion at once, and the pattern in a given direction ("scanning" direction) with a radiation beam. There are so-called scanners in which each of the target portions is illuminated by scanning and synchronously scanning the substrate parallel or non-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0003] A semiconductor substrate on which an IC is manufactured typically exhibits some degree of surface level change. The surface of the substrate is generally not flat. Usually, the surface level varies as a function of position on the substrate around the average level. To some extent, such surface level changes are caused by the substrate manufacturing process. One of the components of the surface level change can be characterized as a (local) curvature of the surface. In practice, the local surface level change due to curvature can extend to tens of nanometers.

[0004] Specifically, in the case of a lithographic apparatus that can achieve critical dimension values comparable to the local curvature, it may be necessary to compensate for this curvature. Because the depth of focus of such a projection system of a lithographic apparatus is relatively shallow, local deviations between the image plane containing the image and the surface level due to curvature can cause local defocus. Thus, the pattern generated on the surface may be inaccurate with respect to the size and / or position of the features of the pattern.

[0005] Since the image generated by the projection system has a fixed shape (ie, usually calibrated towards a flat surface), it is as a function of a substrate with curvature, or a position on the substrate. Exposure on a substrate with varying curvature will result in the focus quality of the resulting pattern image changing as a function of position within the image. Specifically, the edges of the substrate have curvature (change) problems that can affect the likelihood of printing a pattern in the vicinity of these edges of the substrate.

[0006] In the case of the scanner lithography system described above, during scanning, a pattern image is generated by imaging a section of a patterning device (eg mask) onto a substrate. The projected image of this section, referred to herein as the exposure slit, has a rectangular shape. The width of the slit (the width in the direction perpendicular to the scanning direction) corresponds to the width of the exposure field on which the pattern image is formed. The length of the slit in the scanning direction is usually much shorter than the width of the slit. Therefore, the maximum influence of curvature on defocus may occur in the non-scanning direction in some cases.

[0007] Defocus due to curvature along the scanning direction can be compensated to some extent by leveling the substrate relative to the image plane of the projection system as a function of the position of the slit on the substrate. However, in the direction perpendicular to the scanning direction, the curvature may be relatively large and correction may not be possible.

[0008] It would be desirable to have a lithographic apparatus with improved substrate curvature compensation.

[0009] According to one aspect of the present invention, an illumination system configured to condition a radiation beam and a patterning device capable of forming a patterned radiation beam by applying a pattern to a cross section of the radiation beam are supported. A patterning device support configured to hold, a substrate table configured to hold a substrate, and configured to project a patterned radiation beam onto a target portion of the substrate in a scanning exposure along a scanning direction A lithographic apparatus is provided that includes a projection system. The illumination system is configured to form a slit-shaped image having a curved shape with a slit curvature in the scanning direction in the plane of the patterning device. The slit-type image has a length in the scanning direction and has a width substantially perpendicular to the scanning direction. The slit-type image is configured to generate a curved pattern image portion of the patterned radiation beam in the image plane of the projection system.
According to one aspect of the invention, patterning in a step of adjusting a radiation beam, applying a pattern to a cross section of the radiation beam to form a patterned radiation beam, and scanning exposure along a scanning direction Projecting the emitted radiation beam onto a target portion of the substrate and forming a slit-type image, wherein the slit-type image has a length in the scanning direction and is substantially relative to the scanning direction. A slit-shaped image having a curved shape with a slit curvature in the scanning direction and a curved pattern image portion of the patterned radiation beam in the image plane of the projection system A device manufacturing method including the step of disposing a slit-type image. .

[0010] According to one aspect of the invention, a computer program loaded by a computer is provided on a computer-readable medium. The computer includes a processor and a storage device coupled to the processor, and interfaces with the lithographic apparatus to control the lithographic apparatus. The lithographic apparatus includes an illumination system configured to condition the radiation beam, a patterning device support configured to support a patterning device capable of providing a pattern in a cross-section of the radiation beam and forming a patterned radiation beam A body, a substrate table configured to hold a substrate, and a projection system configured to project a patterned radiation beam onto a target portion of the substrate in a scanning exposure along a scanning direction. The illumination system has a curved shape with a slit curvature in the scanning direction, a length in the scanning direction, and a slit-shaped image having a width perpendicular to the scanning direction on the reticle. It is configured to form. The computer is configured as a control system coupled at least to the lighting system to control at least the actions of the lighting system. The processor, when loaded with a computer program, controls the illumination system to form a slit-shaped image and to generate a curved pattern image portion of the patterned radiation beam in the image plane of the projection system. A mold image can be placed.

[0011] According to one aspect of the invention, a computer product is provided that includes machine-executable instructions embedded in a machine-readable medium and configured to perform a device manufacturing method. The device manufacturing method includes forming a slit-type image in a plane of a patterning device in a lithographic apparatus, the patterning device configured to pattern the radiation beam and form a patterned radiation beam Has been. The slit-type image has a length in the scanning direction and has a width substantially perpendicular to the scanning direction. The slit-type image has a curved shape having a slit curvature in the scanning direction. A slit-type image is formed to produce a curved pattern image portion of the patterned radiation beam in the image plane of the projection system.

[0012] According to one aspect of the invention, a patterning device support configured to support a patterning device capable of providing a pattern in a cross-section of a radiation beam to form a patterned radiation beam, and a substrate, A substrate table configured to hold; a projection system configured to project a patterned beam of radiation onto a target portion of the substrate in a scanning exposure along a scanning direction; and an exposure slit in the plane of the patterning device. An lithographic apparatus is provided comprising an illumination system configured to form and illuminate a patterning device. The exposure slit has a curved shape having a slit curvature in the scanning direction, a length in the scanning direction, and a width substantially perpendicular to the scanning direction.

[0013] Embodiments of the present invention are described below with reference to the accompanying schematic drawings, which are merely examples. In the figure, corresponding reference symbols represent corresponding parts.

[0014] FIG. 1 depicts a lithographic apparatus according to one embodiment of the invention. [0015] FIG. 1 illustrates a conventional slit used in a scanner lithographic apparatus. [0016] FIG. 5 illustrates pattern imaging on a non-planar substrate surface. [0017] FIG. 5 illustrates imaging of a pattern onto a non-flat substrate surface. [0018] FIG. 6 illustrates a slit according to an embodiment of the invention. [0019] FIG. 1 depicts a lithographic apparatus according to one embodiment of the invention.

[0020] Figure 1 schematically depicts a lithographic apparatus according to one embodiment of the invention. This apparatus is in accordance with certain parameters constructed to support an illumination system (illuminator) IL, patterning device (eg mask) MA configured to condition a radiation beam B (eg UV radiation or EUV radiation). Constructed to hold a patterning device support or support structure (eg mask table) MT, substrate (eg resist coated wafer) W connected to a first positioner PM configured to accurately position the patterning device A pattern applied to the radiation beam B by the patterning device MA, and a substrate table (eg wafer table) WT connected to a second positioner PW configured to accurately position the substrate according to certain parameters The substrate And a target portion C a projection system configured to project the (e.g. one or more dies are included) (e.g. a refractive projection lens system) PS.

[0021] The illumination system is a refractive optical component, a reflective optical component, a magneto-optical component, an electromagnetic optical component, an electrostatic optical component or other type of optical component, or the like, for guiding, shaping or controlling radiation. Various types of optical components, such as any combination of, can be provided.

[0022] The support structure supports the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions, such as for example whether or not the patterning device is held in a vacuum environment. The support structure can use mechanical clamping techniques, vacuum clamping techniques, electrostatic clamping techniques or other clamping techniques to hold the patterning device. The support structure may be a frame or a table that can be fixed or moved as required, for example. The support structure may ensure that the patterning device is at a desired position, for example with respect to the projection system. Any use of the terms “reticle” or “mask” herein may be considered synonymous with the more general term “patterning device”.

[0023] As used herein, the term "patterning device" refers to any device that can be used to impart a pattern to a cross section of a radiation beam, thereby generating a pattern on a target portion of a substrate. It should be interpreted broadly as meaning. Note that the pattern imparted to the radiation beam does not necessarily correspond exactly to the desired pattern in the target portion of the substrate, for example if the pattern includes phase shift features or so-called assist features. I want to be. The pattern imparted to the radiation beam typically corresponds to a particular functional layer in a device being created in the target portion, such as an integrated circuit.

[0024] The patterning device may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography, and mask types such as binary, alternating Levenson and attenuated phase shift, and various hybrid mask types are known. An example of a programmable mirror array uses micromirrors arranged in a matrix that can be individually tilted so that the incident radiation beam reflects in different directions. This tilted mirror imparts a pattern to the radiation beam reflected by the mirror matrix.

[0025] The term "projection system" as used herein refers to a refractive optical system suitable for the exposure radiation used or other factors such as the use of immersion liquid or the use of a vacuum. Broadly interpreted as encompassing any type of projection system, including reflective optical systems, catadioptric optical systems, magneto-optical systems, electromagnetic optical systems and electrostatic optical systems, or any combination thereof I want to be. Any use of the term “projection lens” herein may be considered as synonymous with the more general term “projection system”.

[0026] As shown in the figure, the device is a transmissive (eg, using a transmissive mask) type device. Alternatively, the device may be of a reflective type (for example using a programmable mirror array of the type referenced above or using a reflective mask).

[0027] The lithographic apparatus may be of a type having two (dual stage) or more substrate tables (and / or a plurality of mask tables). In such a “multi-stage” machine, additional tables can be used in parallel, or for one or more tables while one or more other tables are used for exposure. Preliminary steps can be performed.

[0028] The lithographic apparatus may be of a type in which at least a portion of the substrate is covered with a liquid having a relatively high refractive index, for example water, so that the space between the projection system and the substrate is filled. Good. It is also possible to add immersion liquid to other spaces in the lithographic apparatus, for example, between the mask and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of projection systems. As used herein, the term “immersion” does not imply that a structure, such as a substrate, must be immersed in a liquid, but simply during exposure, between the projection system and the substrate. It just means that the liquid is placed in the.

Referring to FIG. 1, the illuminator IL receives a radiation beam from a radiation source SO. If the radiation source is, for example, an excimer laser, the radiation source and the lithographic apparatus can be separate components. In such a case, the radiation source is not considered to form part of the lithographic apparatus, and the radiation beam is used, for example, using a beam delivery system BD with a suitable guide mirror and / or beam expander. Delivered from the radiation source SO to the illuminator IL. In other cases the source may be an integral part of the lithographic apparatus, for example when the source is a mercury lamp. The radiation source SO and the illuminator IL can be referred to as a radiation system together with a beam delivery system BD, if desired.

[0030] The illuminator IL may include an adjuster AD for adjusting the angular intensity distribution of the radiation beam. In general, at least the outer and / or inner radius range (commonly referred to as σ-outer and σ-inner, respectively) of the intensity distribution in the pupil plane of the illuminator can be adjusted. The illuminator IL may also include various other components such as an integrator IN and a capacitor CO. An illuminator can be used to condition the radiation beam and have a desired uniform intensity distribution in its cross section.

[0031] The radiation beam B is incident on the patterning device support (eg, mask MA), which is held on the patterning device support or support structure (eg, mask table) MT, and is patterned by the patterning device. The radiation beam B transmitted through the patterning device (eg mask) MA passes through a projection system PS that focuses the radiation beam onto a target portion C of the substrate W. The substrate table WT can be accurately moved using the second positioner PW and the position sensor IF (eg interferometer device, linear encoder or capacitive sensor), so that for example different target portions C of the radiation beam B It can be placed in the optical path. Similarly, using a first positioner PM and another position sensor (not explicitly shown in FIG. 1), for example after mechanical retrieval from a mask library or during a scan, the patterning device ( For example, the mask) MA can be accurately positioned with respect to the optical path of the radiation beam B. Typically, movement of the patterning device support or support structure (eg mask table) MT uses a long stroke module (coarse positioning) and a short stroke module (fine positioning) that form part of the first positioner PM. Can be realized. Similarly, the movement of the substrate table WT can be realized using a long stroke module and a short stroke module forming part of the second positioner PW. In the case of a stepper (not a scanner), the patterning device support or support structure (eg mask table) MT can be connected to a short stroke actuator only, or can be fixed. Patterning device (eg mask) MA and substrate W may be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. Although the figure shows a substrate alignment mark that occupies a dedicated target portion, the substrate alignment mark can also be placed in the space between the target portion (such a substrate alignment mark). Is known as the scribe line alignment mark). Similarly, if multiple dies are provided on the patterning device (eg mask) MA, mask alignment marks can be placed between the dies.

[0032] The apparatus shown in the figure can be used in at least one of the modes described below.

[0033] Step mode: The patterning device support or support structure (eg mask table) MT and the substrate table WT are essentially kept stationary, and the entire pattern imparted to the radiation beam is projected onto the target portion C in one go ( Ie single static exposure). Next, the substrate table WT is shifted in the X and / or Y direction and a different target portion C is exposed. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure.

[0034] 2. Scan mode: While the pattern imparted to the radiation beam is projected onto the target portion C, the patterning device support or support structure (eg mask table) MT and the substrate table WT are scanned synchronously (ie single dynamic exposure). . The speed and direction of the substrate table WT relative to the patterning device support or support structure (eg mask table) MT depends on the magnification (reduction factor) and image reversal characteristics of the projection system PS. In scan mode, the maximum size of the exposure field limits the width of the target portion in a single dynamic exposure (width in the non-scan direction), and the length of the scan portion (height in the scan direction). ) Is decided.

[0035] In scanning exposure, the illumination profile of the radiation beam shaped by the illuminator IL disposed above the reticle moves over the reticle, thereby forming an image of the pattern on the wafer. The illuminator IL produces a slit-type image in the conjugate plane of the illumination system, ie, the plane of the reticle (ie, patterning device).

[0036] 3. Other modes: The patterning device support or support structure (eg mask table) MT is essentially kept stationary to hold the programmable patterning device, and the pattern imparted to the radiation beam is projected onto the target portion C. While being in, the substrate table WT is moved or scanned. In this mode, a pulsed radiation source is typically used, and the programmable patterning device is updated as needed during each scan, as the substrate table WT moves, or between successive radiation pulses. This mode of operation can be readily applied to maskless lithography that utilizes programmable patterning device, such as a programmable mirror array of a type as referred to above.

[0037] Combinations and / or variations on the above described modes of use or entirely different modes of use may also be employed.

FIG. 2 a shows a slit type image area SL 0 (referred to as an exposure slit) used in a scanner lithography apparatus according to the prior art.

The exposure slit SL0 is generated by the illuminator IL as described above.

[0040] Normally, the exposure slit SL0 has a substantially rectangular shape having a width WS and a length LS. The exposure slit SL0 is arranged with its length LS parallel to the scanning direction Y. The width WS is substantially equal to the width of the exposure field.

[0041] Although the exposure field may include a plurality of target portions C that are adjacent to each other in the non-scanning direction X, the width of the exposure field may correspond to the width of at least one target portion C. it can.

[0042] Figure 2b shows a first example of imaging a pattern onto a non-planar substrate surface using a conventional exposure slit.

FIG. 2 b shows an outline of a part W 1 of the substrate W in a cross-sectional view along the scanning direction Y. The length WFy of the substrate portion W1 substantially corresponds to the length of the exposure field. As shown in the figure, the substrate portion W1 is not flat, but exhibits the local curvature shown in the vertical direction Z.

[0044] Those skilled in the art will appreciate that the local curvature in a general sense is related to the level change of the surface of the substrate. Curvature as secondary substrate surface non-uniformity is the first non-modifiable element following lower surface non-uniformity as height and slope. In practice, surface level changes can extend to tens of nanometers.

[0045] The vertical line FP shown above the substrate portion W1 indicates the image plane (ie, the focal plane) of the projection system.

Further, a part of the pattern image portion PT exposed through the exposure slit SL0 is indicated by the position of the end of the slit according to the conventional technique.

[0047] During a scanning operation in which a pattern is exposed on the substrate, the lithographic apparatus brings at least the portion of the substrate that is actually exposed within the distance range of the image plane, which is less than a predetermined defocus error value. The pattern image is configured to be exposed with an out-of-focus error. This operation, known as leveling, typically uses a substrate surface map that contains measurement data for the surface level as a function of position on the substrate. This surface map can be created prior to the actual scanning exposure, but it is alternatively possible to create the surface map “on the fly” or dynamically, ie during the scanning exposure. Those skilled in the art will understand how to create a surface map under these alternative conditions.

[0048] During scanning, based on this substrate surface map, the surface level is adjusted by correlating the substrate surface map data with the actual position of the image portion projected onto the substrate during the scan. This leveling operation typically includes adjustment by translation along the Z direction to adjust the height and adjustment by rotation about the X and / or Y directions. Thus, these substrate adjustments, such as substrate adjustment in the Z direction and rotation around the X and / or Y directions, can ensure that the illuminated portion of the substrate is placed in an optimal position relative to the image focal plane. .

[0049] Figure 2c shows a second example of imaging a pattern onto a non-planar substrate surface using a conventional slit.

FIG. 2 c shows an outline of a part W 1 of the substrate W in a cross-sectional view along the non-scanning direction X. The length WFx of the substrate portion substantially corresponds to the width of the exposure field. As shown, the substrate portion W1 is not flat, but shows a local height change shown in the vertical direction Z.

[0051] The vertical line FP shown above the substrate portion indicates the image plane of the projection system. Note that the image plane of the projection system can be curved in any way. Usually, the lens is set so that the image surface and the plane correspond as closely as possible.

Further, a part of the pattern image portion PT to be exposed is indicated by the position of the end of the slit according to the prior art. In the non-scanning direction X, the exposure slit SL0 has a width substantially equal to the width of the exposure field, so it is desirable to compensate for surface level changes across the width of the exposure slit SL0.

[0053] In order to have an allowable maximum defocus error across the width of the exposure field in the non-scanning direction X, the position of the image plane FP is such that a portion of the cross-section is located above the surface level and other The portion is selected to be at an optimal level position below the surface level. As a result, some will show a local defocus error as shown by arrow DF.

[0054] Since the width WS of the exposure slit SL0 substantially corresponds to the width of the exposure field, there is a limit to the correction of the surface level change by the leveling operation described above.

FIG. 3 shows an exposure slit according to an embodiment of the present invention.

The exposure slit SL according to one embodiment of the present invention has a curved shape having a curvature ΔY in the scanning direction Y. The exposure slit has a length LS along the scanning direction Y, and a width WS in the non-scanning direction X.

[0057] In one embodiment, the length LS is substantially constant over the entire width WS of the exposure slit. The width WS can correspond to the width of the exposure field.

[0058] In other embodiments, the length LS can be varied along the non-scanning direction to compensate for radiation dose changes induced by curved slit shapes.

[0059] By using the exposure slit SL curved in the scanning direction Y, the substrate curvature in the Z direction along the non-scanning direction X can be compensated by tilting the substrate along the X direction during scanning. Benefits are gained. It will also be appreciated that the curvature along the scanning direction Y can still be compensated in the same way as is done using conventional slits.

[0060] In this embodiment, the curvature of the exposure slit SL is constant. The pattern image that has passed through the slit will have a curved pattern image shape in the image plane FP that is still flat in the Z direction.

[0061] In order to compensate for the curvature in the Z direction along the non-scanning direction X, the lithographic apparatus uses a substrate table WT tilted by Rx along the non-scanning direction X to a surface level or topology at the tilted position. The curved pattern image shape is provided in a manner that is substantially aligned with the projected image plane.

[0062] Thus, in this embodiment, the lithographic apparatus determines the height of the substrate surface relative to the level of the flat image plane (the height in the Z direction) as a function of the actual position of the image portion on the substrate during scanning. Can be adjusted. Further, the lithographic apparatus provides a tilt of the substrate based on the curvature of the entire exposure field during exposure.

[0063] The ability to provide a tilt Rx about an axis that is substantially perpendicular to the scanning direction and substantially parallel to the surface of the substrate and to adjust the height of the surface of the substrate is Can be achieved by the parts building table.

[0064] The curvature of the surface may be convex or concave. As will be appreciated by those skilled in the art, the tilt of the substrate along the X direction can be matched to the level of the image plane with either a convex or concave surface.

In one embodiment, the substrate curvature in the Z direction along the X direction is about −50 nm to about 50 nm with respect to the slit width WS. The substrate table WT can be configured to provide a maximum tilt angle Rx, max of up to about 50 μrad (50 × 10 ⁻⁶ rad) as compensation. This maximum inclination angle Rx, max corresponds to the maximum substrate curvature along the X direction divided by the curvature ΔY of the curved exposure slit SL.
Rx, max = 50 × 10 ⁻⁹ / ΔY (Formula 1)
(Unit of ΔY is meter)

[0066] By tilting by a certain angle Rx, a slight decline may occur in the pattern image during exposure depending on the actual value of Rx. Decay is related to the change in focus error along the scanning direction, while defocus is defined as the average focus error along the non-scanning direction. In the case of an exposure slit with a slit length of LS and the maximum tilt angle mentioned above, the induced decay is
Rx × LS = 50 × 10 ⁻⁹ × LS / ΔY (Formula 2)
Given in.

[0067] In one exemplary embodiment, a decline of Rx x LS with a value of about 15 x ^10-9 m may be allowed. Under these conditions, for a given local curvature (eg 50 nm) and a given Rx, max (eg 50 μrad) and for a given slit length LS of eg 2.5 mm, an exposure slit of about 8 mm Is obtained.

[0068] It should be noted that focus control can be improved using an exposure slit according to an embodiment of the present invention. Also, the curved shape of the slits can reduce the size of the optical components of the projection system and thus suppress some projection system aberrations related to size.

[0069] An exposure slit according to an embodiment of the present invention is not limited to a parabolic curvature in the XY plane (ie, Y≡X2), and can generally be associated with an exposure slit SL of any non-linear shape. Please note that.

[0070] In one embodiment, a V-shaped exposure slit SL can be provided. Alternatively, a stepwise exposure slit SL can be provided on the XY plane.

[0071] According to one embodiment of the present invention, a method for leveling a substrate during a scanning exposure is provided. According to this method, a slit SL having a curved shape is provided as a scanner slit.

[0072] According to this method, there is provided a step of projecting a pattern image onto the surface of a substrate using a scanning exposure in the scanning direction Y, using a curved shaped exposure slit SL according to an embodiment of the present invention. The pattern image is exposed.

The pattern image includes a curved pattern image in the image plane of the projection system for exposure by the curved shape exposure slit SL.

[0074] According to the above method, the scanning data of the position of the projection pattern image along the scanning path on the substrate is obtained while scanning the substrate in the lithographic apparatus as described above. Provided.

[0075] According to this method, a step is then provided for measuring the surface shape of the substrate, after which the measurement data is displayed on a substrate surface map or as described above, Used on-the-fly.

[0076] According to this method, a step of comparing the scanning data of the position of the projection pattern image along the scanning path and the measurement data of the substrate surface map is then provided.

[0077] According to this method, for each position along the scan path, the step of adjusting the height of the surface level of the substrate relative to the level of the image plane onto which the pattern image is projected is provided.

[0078] The method further provides a step of tilting the substrate, ie, tilting the substrate about the X axis by Rx (along the non-scanning direction X). The value of the tilt angle is determined from the curvature value of the exposure field being exposed. This method provides a tilt angle value that can substantially match the curved surface level or topology at that tilt position with the topology of the image plane containing the curved pattern image.

According to this method, the curvature value of the entire exposure field can be derived from the substrate surface map.

[0080] According to the method of one embodiment of the present invention, leveling (ie adjusting the height of the surface level and tilting the substrate) can be achieved by adjusting the Rx slope relative to the local curvature, local slope and height of the surface. Note that and optimization of decline.

[0081] Furthermore, this method can provide either static or dynamic correction during scanning exposure.

[0082] In the static correction mode, the average Rx slope is calculated for each field, and thus the average curvature is corrected for each field. In the dynamic correction mode, continuous optimization along the scan path is performed and the Rx slope is continuously adapted based on the local curvature in the field.

In addition, an embodiment of the present invention relates to a computer program that enables execution of the above-described method by a lithographic apparatus that includes a curved-shaped exposure slit SL having a curvature ΔY in the scanning direction.

[0084] In other embodiments, the curvature of the exposure slit SL is variable and can be adapted by relative positioning of the reticle masking blades. Curvature adaptation can be performed on a field-by-field basis or during a scan.

[0085] In an embodiment, in order to carry out the method described above, the lithographic apparatus may comprise a computer structure CA comprising a processor PR and a storage device ME for performing arithmetic operations. FIG. 4 schematically shows this, which shows an example of a lithographic apparatus further comprising a processor PR adapted to communicate with a storage device ME. The storage device ME is optional, such as a tape device, hard disk, read only memory (ROM), electrically erasable programmable read only memory (EEPROM) and random access memory (RAM), which is adapted to store instructions and data. Types of storage devices can be used.

[0086] The processor PR reads and executes the programming lines stored in the storage device ME, which provide the processor PR with the functions for controlling the lithographic apparatus and performing the method described above. Can be configured.

[0087] The processor PR interfaces with the lithographic apparatus (represented schematically by arrows A1, A2) so that the above method can be performed, and the projection pattern image along the path of the scan on the substrate. Scanning data relating to the position of the substrate is acquired and at least a portion of the substrate table WT is controlled.

[0088] The position of the substrate table is related to the position defined in the X, Y, Z coordinates and at least the tilt angle Rx along the X direction.

[0089] The processor PR also has access to a surface map database that contains the substrate surface map of the measurement data for the surface level as a function of the position on the substrate, present in the storage device ME. . Note that the processor can create a surface map prior to the actual scanning exposure and store the results in a surface map database.

[0090] Alternatively, the processor can also create a surface map "on the fly", in which case surface level measurements as a function of position on the substrate are obtained during scanning exposure. The measured value is used.

[0091] The processor PR may be, among other things, a processor provided to perform one or more of the method embodiments described above, but the processor PR as a whole is a lithographic apparatus. It may be a central processing unit adapted to control, in which case it will be provided with additional functions for performing one or more of the embodiments described above.

[0092] It should be understood that many more units and / or other units such as storage devices, input devices and readout devices known to those skilled in the art may be provided. Further, if necessary, one or more of them can be arranged at a position away from the processor PR. Although the processor PR is shown as a box in the figure, the processors PR operate in a parallel or master-slave structure and can be remotely located from each other as known to those skilled in the art. The processing apparatus can be provided.

[0093] Although the connections in FIG. 4 are all shown as wired connections, it has been found that one or more of these connections can be a wireless connection. These connections are merely intended to indicate that “connected” units are intended to communicate with each other in some way. The computer system may be any signal processing system using analog and / or digital and / or software techniques adapted to perform the functions described herein.

[0094] The computer system shown in FIG. 4 is adapted to perform calculations according to the method of one embodiment of the invention. A computer system can execute a computer program (or program code) residing on a computer-readable medium. When this computer program (or program code) is loaded into a computer system, the computer system can execute a method according to an embodiment of the present invention.

[0095] Reference is made herein to, among other things, the use of a lithographic apparatus in the manufacture of ICs, but the lithographic apparatus described herein includes an inductive and detection pattern for an integrated optical system, a magnetic domain memory, It should be understood that other applications such as the manufacture of flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc. can be had. In the context of such alternative applications, any use of the terms “wafer” or “die” herein may be considered synonymous with the more general terms “substrate” or “target portion”, respectively. Those skilled in the art will understand that this is possible. The substrate referred to herein may be, for example, a track (usually a tool that applies a layer of resist to the substrate and develops the exposed resist), metrology tool and / or inspection tool, before exposure. Or it can process after exposure. Where applicable, the disclosure herein may be applied to such substrate processing tools and other substrate processing tools. Also, since the substrate can be processed multiple times, for example to produce a multi-layer IC, the term substrate used herein refers to a substrate that already contains multiple processed layers. Sometimes pointing.

[0096] Also, although the use of embodiments according to the present invention is particularly referred to in the context of optical lithography, the present invention can be used in other applications, such as imprint lithography, and is context-acceptable. It will be understood that the invention is not limited to optical lithography. In the case of imprint lithography, the pattern produced on the substrate is defined by the topography of the patterning device. The topography of the patterning device is pressed into a layer of resist being applied to the substrate, and then electromagnetic radiation, heat, pressure, or a combination thereof is applied to cure the resist. When the resist is cured, the patterning device is removed from the resist, leaving behind a pattern.

[0097] As used herein, the terms "radiation" and "beam" include ultraviolet (UV) radiation (eg, radiation having a wavelength of about 365 nm, 355 nm, 248 nm, 193 nm, 157 nm or 126 nm), and All types of electromagnetic radiation are included, including extreme ultraviolet (EUV) radiation (e.g. radiation with a wavelength range of 5-20 nm), as well as particle beams such as ion beams or electron beams.

[0098] Where the context allows, the term "lens" refers to any of various types of optical components, including refractive optical components, reflective optical components, magneto-optical components, electromagnetic optical components, and electrostatic optical components. Means one or a combination of

[0099] While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. For example, the present invention may take the form of a computer program that includes one or more machine-readable instruction sequences describing the methods disclosed above, or a data storage medium (eg, such as one that stores such a computer program). Semiconductor memory device, magnetic disk or optical disk).

[00100] The above description is intended to be illustrative and does not limit the invention. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described above without departing from the scope of the claims set forth below.

Claims (17)

An illumination system configured to condition the radiation beam;
A patterning device support configured to support a patterning device capable of imparting a pattern to a cross-section of the radiation beam to form a patterned radiation beam;
A substrate table configured to hold a substrate;
A projection system configured to project the patterned beam of radiation onto a target portion of the substrate in a scanning exposure along a scanning direction;
The illumination system is configured to form a slit-type image having a curved shape with a slit curvature in the scanning direction on a plane of the patterning device;
The slit-type image has a length in the scanning direction and has a width substantially perpendicular to the scanning direction, and the slit-type image is curved of the patterned radiation beam. A lithographic apparatus configured to generate a pattern image portion in an image plane of the projection system.   The substrate table can align the curved pattern image portion of the patterned radiation beam in the image plane of the projection system with the surface level of the surface portion illuminated by the patterned radiation beam. , Configured to tilt the surface of the substrate about an axis that is substantially perpendicular to the scanning direction and substantially parallel to the surface of the substrate, wherein the tilt of the surface of the substrate is The lithographic apparatus according to claim 1, determined by a local surface curvature along the scanning direction of the surface level of the surface portion.   The substrate table is configured to adjust a surface level height of a surface portion illuminated by the patterned radiation beam, the height adjustment being determined by a local level of the surface level of the surface portion. The lithographic apparatus according to claim 1.   2. The illumination system of claim 1, wherein the illumination system is configured to form the slit-type image such that the curved slit curvature is fixed during the scanning exposure to the target portion of the substrate. The lithographic apparatus described.   The illumination system is configured to adapt the curved curvature of the curved shape along the scanning direction during the scanning exposure, the slit curvature being along the scanning direction of the surface level of the surface portion. A lithographic apparatus according to claim 1, adapted by determining a local surface curvature. Adjusting the radiation beam;
Applying a pattern to a cross-section of the radiation beam to form a patterned radiation beam;
Projecting the patterned beam of radiation onto a target portion of a substrate in a scanning exposure along a scanning direction;
Forming a slit-type image, wherein the slit-type image has a length in the scanning direction and has a width substantially perpendicular to the scanning direction; An image has a curved shape having a slit curvature in the scanning direction, and the slit-shaped image is formed to generate a curved pattern image portion of the patterned radiation beam in an image plane of a projection system; A device manufacturing method comprising:   In the scanning direction, the curved pattern image portion of the patterned radiation beam in the image plane of the projection system and the surface level of the surface portion illuminated by the patterned radiation beam can be aligned. Inclining the surface of the substrate about an axis substantially perpendicular to the surface and substantially parallel to the surface of the substrate, the inclining step at the surface level of the surface portion. The device manufacturing method according to claim 6, comprising determining a local surface curvature along the scanning direction.   7. The method of claim 6, comprising adjusting a surface level height of a surface portion illuminated by the patterned radiation beam, wherein the adjusting step is determined by a local level of the surface level of the surface portion. The device manufacturing method as described.   Adapting the curved curvature of the slit along the scanning direction during the scanning exposure, the adapting step comprising adjusting a local surface curvature along the scanning direction of the surface level of the surface portion. The device manufacturing method according to claim 8, comprising a determining step. Creating a surface map of the surface level surface level data of the substrate as a function of position on the substrate;
The device manufacturing method according to claim 9, wherein the surface level data relates to the local surface curvature of the surface portion along the scanning direction of the surface level. A computer program on a computer readable medium loaded by a computer, the computer comprising a processor and a storage device connected to the processor, and the computer comprising:
An illumination system configured to condition the radiation beam;
A patterning device support configured to support a patterning device capable of imparting a pattern to a cross-section of the radiation beam to form a patterned radiation beam;
A substrate table configured to hold a substrate;
Interfacing with a lithographic apparatus comprising: a projection system configured to project the patterned beam of radiation onto a target portion of the substrate in a scanning exposure along a scanning direction;
The illumination system has a curved shape having a slit curvature in the scanning direction, has a length in the scanning direction, and has a width substantially perpendicular to the scanning direction. Is formed in the plane of the patterning device,
The computer is configured as a control system for controlling at least the lighting system;
When the computer program is loaded, it enables the processor to control the lighting system;
Forming the slit-type image, and
A computer program adapted to position the slit-type image to produce a curved pattern image portion of the patterned radiation beam in an image plane of the projection system.   The computer is configured to control the substrate table, and the computer program allows the processor to control the substrate table, thereby the curvature of the patterned radiation beam in the image plane of the projection system. A pattern image portion and a surface level of a surface portion illuminated by the patterned radiation beam can be aligned substantially perpendicular to the scanning direction and substantially on the surface of the substrate. The surface of the substrate can be tilted about an axis parallel to the surface, the tilt of the surface of the substrate being determined by a local surface curvature along the scanning direction of the surface level of the surface portion. The computer program according to claim 11. A computer product embedded in a machine-readable medium,
Forming a slit-type image in a plane of a patterning device in a lithographic apparatus, wherein the patterning device is configured to pattern a radiation beam to form a patterned radiation beam; Has a length in the scanning direction and has a width substantially perpendicular to the scanning direction, and the slit-shaped image is curved with a slit curvature in the scanning direction. Having a shape and configured to perform a device manufacturing method comprising: forming the slit-shaped image to generate a curved pattern image portion of the patterned radiation beam in an image plane of a projection system. Computer products containing machine executable instructions. The method comprises
Adjusting the radiation beam;
Patterning the radiation beam to form the patterned radiation beam;
The computer product of claim 13, further comprising: projecting the patterned beam of radiation onto a target portion of a substrate in a scanning exposure along a scanning direction. A patterning device support configured to support a patterning device capable of imparting a pattern to a cross-section of the radiation beam and capable of forming a patterned radiation beam;
A substrate table configured to hold a substrate;
A projection system configured to project the patterned beam of radiation onto a target portion of the substrate in a scanning exposure along a scanning direction;
An illumination system configured to form an exposure slit in a plane of the patterning device and irradiate the patterning device, wherein the exposure slit has a curved shape having a slit curvature in the scanning direction, An lithographic apparatus comprising: an illumination system having a length and a width substantially perpendicular to the scanning direction.   16. The lithographic apparatus according to claim 15, wherein the curved slit curvature is fixed during the scanning exposure to the target portion of the substrate.   The lithographic apparatus according to claim 15, wherein the illumination system is configured to adapt the slit curvature along the scanning direction during the scanning exposure.

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